Thin film dielectric composite materials

ABSTRACT

A dielectric composite material comprising at least two crystal phases of different components with TiO 2  as a first component and a material selected from the group consisting of Ba 1−x Sr x TiO 3  where x is from 0.3 to 0.7, Pb 1−x Ca x TiO 3  where x is from 0.4 to 0.7, Sr 1−x Pb x TiO 3  where x is from 0.2 to 0.4, Ba 1−x Cd x TiO 3  where x is from 0.02 to 0.1, BaTi 1−x Zr x O 3  where x is from 0.2 to 0.3, BaTi 1−x Sn x O 3  where x is from 0.15 to 0.3, BaTi 1−x Hf x O 3  where x is from 0.24 to 0.3, Pb 1−1.3x La x TiO 3+0.2x  where x is from 0.23 to 0.3, (BaTiO 3 ) x (PbFeo 0.5 Nb 0.5 O 3 ) 1−x  where x is from 0.75 to 0.9, (PbTiO 3 ) − (PbCo 0.5 W 0.5 O 3 ) 1−x  where x is from 0.1 to 0.45, (PbTiO 3 ) x (PbMg 0.5 W 0.5 O 3 ) 1−x  where x is from 0.2 to 0.4, and (PbTiO 3 ) x (PbFe 0.5 Ta 0.5 O 3 ) 1−x  where x is from 0 to 0.2, as the second component is described. The dielectric composite material can be formed as a thin film upon suitable substrates.

The present invention relates to dielectric composite materials and moreparticularly to thin film dielectric composite materials. This inventionwas made with government support under Contract No. W-7405-ENG-36awarded by the U.S. Department of Energy. The government has certainrights in the invention.

FIELD OF THE INVENTION BACKGROUND OF THE INVENTION

Materials with a high, nonlinear dielectric constant have been found tobe very beneficial when used for microelectronic applications in theradio frequency and/or microwave frequency regime. Materials that havebeen widely investigated for these applications include strontiumtitanate (SrTiO₃), barium strontium titanate (BA_(1−x)Sr_(x)TiO₃ alsoreferred to as BSTO), lead calcium titanate (Pb_(1−x)Ca_(x)TiO₃), andthe like.

By far the most widely investigated materials for electrically tunablemicrowave devices are Ba_(1−x)Sr_(x)TiO₃. The operation temperature ofthe devices is largely determined by the ratio of Ba to Sr. Thesematerials however exhibit a high dielectric loss which is undesirablefor high performance microwave devices. For practical dc electricallytunable microwave devices (such as voltage tunable filters and phaseshifters), it is desirable to have nonlinear dielectric materials thathave as large a dielectric tunability and as low a dielectric loss aspossible. The existing efforts to reduce the dielectric loss includeadding dopants such as tungsten, manganese, and/or calcium intoBa_(1−x)Sr_(x)TiO₃. Other dopants have also been introduced into BSTOmaterials in an attempt to improve the material properties that aredirectly related to device performance. For example, U.S. Pat. Nos.5,312,790, 5,427,988, 5,486,491, 5,635,433, 5,635,434, 5,693,429,5,830,591 and 5,846,893 describe BSTO composites including additives ordopants such as magnesium oxide, aluminum oxide, zinc oxide, zirconiumoxide, magnesium zirconate, magnesium aluminate, or magnesium titanate.Nevertheless, the existing approaches all suffer from the reduction ofthe dielectric constant and the dielectric tunability. In the lattercase, the dielectric constant for these oxides is typically 10-20. Thedielectric constant of solid solution Ba_(1−x)Sr_(x)TiO₃ varies due tocomposition and temperature, but is typically over 100. Therefore,depending upon the method of mixing and the quantity of dopant, thedielectric constant of composite materials is expected to decreasesignificantly.

A number of references have discussed altering the ratio of Ti to(Ba+Sr). For example, fin et al., Appi. Phys. Lett., vol. 76, no. 5, pp.625-627 (2000) describe films with controlled compositions of Ti to(Ba+Sr) grown from a stoichiometric Ba_(0.5)Sr_(0.5) ₅TiO₃ target.

The common expectation of adding TiO₂ to Ba_(1−x)Sr_(x)TiO₃ is that asingle Ti-rich compound Ba_(1−x)Sr_(x)Ti_(1+y)O₃ phase will form. Incontrast, the present inventors have now discovered that addition ofTiO₂ to Ba_(1−x)Sr_(x)TiO₃ can form a two phase composite material evenunder high temperature processing conditions. In other words, theresultant material maintains separated phases of TiO₂ andBa_(1−x)Sr_(x)TiO₃. This surprising observation led to the developmentof the present invention that shows many advantages compared to existingtechnologies.

One object of the present invention is to provide dielectric compositematerials including two distinct material phases.

Another object of the present invention is to provide thin filmdielectric composite materials including two distinct material phases.

A further object of this invention is to provide epitaxial and/oramorphous, polycrystalline, nanocrystalline thin film dielectriccomposite materials including two distinct material phases.

Yet another object of this invention is to provide dielectric compositematerials having lower dielectric loss and adjustable dielectrictunability.

Yet another object of this invention is to provide dielectric compositematerials having a low dielectric loss and an adjustable dielectricconstant.

SUMMARY OF THE INVENTION

To achieve the foregoing and other objects, and in accordance with thepurposes of the present invention, as embodied and broadly describedherein, the present invention provides a dielectric composite materialincluding at least two crystal phases of different components with TiO₂as a first component and a material selected from the group consistingof Ba_(1−x)Sr_(x)TiO₃ where x is from 0.3 to 0.7, Pb_(1−x)Ca_(x)TiO₃where x is from 0.4 to 0.7, Sr_(1−x)Pb_(x)TiO₃ where x is from 0.2 to0.4, Ba_(1−x)Cd_(x)TiO₃ where x is from 0.02 to 0.1, BaTi_(1−x)Zr_(x)O₃where x is from 0.2 to 0.3, BaTi_(1−x)Sn_(x)O₃ where x is from 0.15 to0.3, BaTi_(1−x)Hf_(x)O₃ where x is from 0.24 to 0.3,Pb_(1−1.3x)La_(x)TiO_(3+0.2x) where x is 0.3,(BaTiO₃)_(x)(PbFe_(0.5)Nb_(0.5)O₃)_(1−x) where x is from 0.75 to 0.9,(PbTiO₃)_(x)(PbC_(0.5)W_(0.5)O₃)_(1−x) where x is from 0.1 to 0.45,(PbTiO₃)_(x)(PbMg_(0.5)W_(0.5)O₃)_(1−x) where x is from 0.2 to 0.4, and(PbTiO₃)_(x)(PbFe_(0.5)Ta_(0.5)O₃)_(1−x) where x is from 0 to 0.2, asthe second component.

In another embodiment, the present invention provides a dielectriccomposite material including at least two crystal phases of differentcomponents, formed at high temperatures from TiO₂ and a materialselected from the group consisting of Ba_(1−x)Sr_(x)TiO₃ where x is from0.3 to 0.7, Pb_(1−x)Ca_(x)TiO₃ where x is from 0.4 to 0.7,Sr_(1−x)Pb_(x)TiO₃ where x is from 0.2 to 0.4, Ba_(1−x)Cd_(x)TiO₃ wherex is from 0.02 to 0.1, BaTi_(1−x)Zr_(x)O₃ where x is from 0.2 to 0.3,BaTi_(1−x)Sn_(x)O₃ where x is from 0.15 to 0.3, BaTi_(1−x)Hf_(x)O₃ wherex is from 0.24 to 0.3, Pb_(1−1.3x)La_(x)TiO_(3+0.2x) where x is from0.23 to 0.3, (BaTiO₃)_(x)(PbFe_(0.5)Nb_(0.5)O₃)_(1−x) where x is from0.75 to 0.9, (PbTiO₃)_(x)(PbCo_(0.5)W_(0.5)O₃)_(1−x) where x is from 0.1to 0.45, (PbTiO₃)_(x)(PbMg_(0.5)W_(0.5)O₃)_(1−x) where x is from 0.2 to0.4, and (PbTiO₃)_(x)(PbFe_(0.5)Ta_(0.5) ₃)_(1−x) where x is from 0 to0.2.

The present invention also provides a process of forming a thin filmdielectric composite material including at least two crystal phases ofdifferent components with TiO₂ as a first component and a materialselected from the group consisting of Ba_(1−x)Sr_(x)TiO₃ where x is from0.3 to 0.7, Pb_(1−x)Ca_(x)TiO₃ where x is from 0.4 to 0.7,Sr_(1−x)Pb_(x)TiO₃ where x is from 0.2 to 0.4, Ba_(1−x)Cd_(x)TiO₃ wherex is from 0.02 to 0.1, BaTi_(1−x)Zr_(x)O₃ where x is from 0.2 to 0.3,BaTi_(1−x)Sn_(x)O₃ where x is from 0.15 to 0.3, BaTi_(1−x)Hf_(x)O₃ wherex is from 0.24 to 0.3, Pb_(1−1.3x)La_(x)TiO_(3+0.2x)where x is from 0.23to 0.3, (BaTiO₃)_(x)(PbFe_(0.5)Nb_(0.5)O₃)_(1−x) where x is from 0.75 to0.9, (PbTiO₃)_(x)(PbCo_(0.5)W_(0.5)O₃)_(1−x) where x is from 0.1 to0.45, (PbTiO₃)_(x)(PbMg_(0.5)W_(0.5)O₃)_(1−x) where x is from 0.2 to0.4, and (PbTiO₃)_(x)(PbFe_(0.5)Ta_(0.5)O₃)_(1−x) where x is from 0 to0.2, as the second component including the steps of forming a startingmaterial including a mixture of TiO₂ and the material selected from thegroup consisting of Ba_(1−x)Sr_(x)TiO₃, Pb_(1−x)Ca_(x)TiO₃,Sr_(1−x)Pb_(x)TiO₃, Ba_(1−x)Cd_(x)TiO₃, BaTi_(1−x)Zr_(x)O₃,BaTi_(1−x)Sn_(x)O₃, BaTi_(1−x)Hf_(x)O₃, Pb_(1−1.3x)La_(x)TiO_(3+0.2x),(BaTiO₃)_(x)(PbFe_(0.5)Nb_(0.5)O₃)_(1−x),(PbTiO₃)_(x)(PbMg_(0.5)W_(0.5)O₃)_(1−x), and(PbTiO₃)_(x)(PbFe0.5Ta_(0.5)O₃)_(1−x) , depositing a thin film of thestarting material on a substrate and heating the thin film of startingmaterial for time and at temperatures sufficient to form said thin filmdielectric composite material including at least two crystal phases ofdifferent components.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph plotting a X-ray diffraction scan of a 90 percent byweight BSTO/10 percent by weight TiO₂ composite on a MgO substrate inaccordance with an embodiment of the present invention.

FIG. 2 is a graph plotting a X-ray diffraction scan of a 50 percent byweight BSTO/50 percent by weight TiO₂ composite on a MgO substrate inaccordance with an embodiment of the present invention.

FIG. 3 shows a coplanar waveguide structure as constructed in thepresent invention.

FIG. 4 is a graph plotting capacitance (femtoFarads (fF)) versuselectric field for a 100 percent BSTO sample, a 90 percent by weightBSTO/10 percent by weight TiO₂ composite sample, and a 50 percent byweight BSTO/50 percent by weight TiO₂ composite sample.

FIG. 5 is a graph plotting dielectric loss versus electric field for a100 percent BSTO sample and a 90 percent by weight BSTO/10 percent byweight TiO₂ composite sample.

DETAILED DESCRIPTION

The present invention concerns thin film and/or ceramic composites thatcan be used for radio frequency and microwave frequency components. Thisinvention provides an effective approach to control the dielectricconstant, the dielectric tunability, and the dielectric loss of thematerials.

Thin film and/or ceramic composites for radio frequency and microwavefrequency components have been designed and fabricated. These componentscan be resonators, filters, phase shifters and the like. The operatingtemperature of the system can be altered based on the exact chemicalcompositions of the composites. Compared to the commonly used dielectricmaterials, the composite materials developed here have the advantages oflower dielectric loss (while maintaining a significantly adjustabledielectric constant) and desirable capacitance tunability.

The composites in the present invention include combinations of titaniumdioxide (TiO₂) and a material such Ba_(1−x)Sr_(x)TiO₃,Pb_(1−x)Ca_(x)TiO₃, Sr_(1−x)Pb_(x)TiO₃, Ba_(1−x)Cd_(x)TiO₃,BaTi_(1−x)Zr_(x)O₃, BaTi_(1−x)Sn_(x)O₃, BaTi_(1−x)Hf_(x)O₃,Pb_(1−1.3x)La_(x)TiO_(3+0.2x), (BaTiO₃)_(x)(PbFe_(0.5)Nb_(0.5)O₃)_(1−x),(PbTiO₃)_(x)(PbCo_(0.5)W_(0.5)O₃)_(1−x),(PbTiO₃)_(x)(PbMg_(0.5)W_(0.5)O₃)_(1−x), and(PbTiO₃)_(x)(PbFe_(0.5)Ta_(0.5)O₃)_(1−x). For the applications of thepresent invention when Ba_(1−x)Sr_(x)TiO₃ is combined with the TiO₂, xis generally from about 0.3 to 0.7 so as to provide an operatingtemperature range above the Curie temperature of the material. For theother materials the ranges of x is generally as follows so as to providean operating temperature range above the Curie temperature of thematerial: for Pb_(1−x)Ca_(x)TiO₃ x is from 0.4 to 0.7; forSr_(1−x)Pb_(x)TiO₃ x is from 0.2 to 0.4; for Ba_(1−x)Cd_(x)TiO₃ x isfrom 0.02 to 0.1; for BaTi_(1−x)Zr_(x)O₃ x is from 0.2 to 0.3; forBaTi_(1−x)Sn_(x)O₃ x is from 0.15 to 0.3; for BaTi_(1−x)Hf_(x)O₃ x isfrom 0.24 to 0.3; for Pb_(1−1.3x)La_(x)TiO_(3+0.2x) x is from 0.23 to0.3; for (BaTiO₃)_(x)(PbFe_(0.5)Nb_(0.5)O₃)_(1−x) x is from 0.75 to 0.9;for (PbTiO₃)_(x)(PbCo_(0.5)W_(0.5)O₃)_(1−x) x is from 0.1 to 0.45; for(PbTiO₃)_(x)(PbMg_(0.5)W_(0.5)O₃)_(1−x) x is from 0.2 to 0.4; and, for(PbTiO₃)_(x)(PbFe_(0.5)Ta_(0.5)O₃)_(1−x) x is from 0 to 0.2. The presentcomposite materials can serve as room temperature tunable dielectricmaterials.

In certain applications of the present invention such as for use as atunable dielectric material, the composite material is preferablyepitaxial as that will improve the tunability as is well known to thoseskilled in the art. The term “epitaxial” generally refers to a materialhaving an oriented crystalline arrangement. Suitable substrate materialsfor epitaxial films include lanthanum aluminum oxide (LaAlO₃), magnesiumoxide (MgO), neodymium gadolinium oxide (NdGaO₃), Sr₂AlTaO₆, or(LaAlO₃)_(0.3)(Sr₂AlTaO₆)_(0.7). The substrate materials can be singlecrystal materials, e.g., a Y₂O₃ single crystal, a SrTiO₃ single crystal,a LaGaO₃ single crystal, an Al₂O₃ single crystal and a ZrO₂ singlecrystal.

In other applications of the present invention such as for use as acapacitor material, the composite material can be amorphous,polycrystalline or nanocrystalline as that may facilitate processing asis well known to those skilled in the art. Suitable substrate materialsfor amorphous, polycrystalline or nanocrystalline films can include asemiconductor material such as a silicon-based material, i.e., a bulksilicon substrate, a silicon germanium substrate, a silicon on insulator(SOI) substrate and the like, an insulator material such as sapphire andthe like, or a metal or metal alloy such as steel and the like.

Thin film dielectric composite materials can be deposited by pulsedlaser deposition or by other well known methods such as evaporation,sputtering, or chemical vapor deposition such as MOCVD. Otherconventional processing techniques can be used for bulk articles andthick films. For example, standard tape casting techniques can be usedfor thick films of several microns in thickness.

The two phase systems of the present invention can be formed in hightemperature processes including, e.g., pulsed laser deposition and thelike. By “high temperature” is generally meant temperatures from about500° C. to about 950° C. although higher temperatures can be employed insome instances. Despite such high temperatures, two phases, e.g., twocrystalline phases of the composite material can be obtained.

In pulsed laser deposition, powder of the desired materials, e.g., TiO₂and Ba_(1−x)Sr_(x)TiO₃ can be initially pressed into a disk or pelletunder high pressure, generally above about 500 pounds per square inch(PSI) and the pressed disk then sintered in an oxygen-containingatmosphere for at least about one hour, preferably from about 12 to 24hours. An apparatus suitable for the pulsed laser deposition is shown inAppl. Phys. Lett., 56, 578(1990), “Effects of beam parameters on excimerlaser deposition of YBa₂Cu₃O_(7−x)”, such description herebyincorporated by reference.

Suitable conditions for pulsed laser deposition include, e.g., thelaser, such as a XeCl excimer laser (20 nanoseconds (ns), 308 nanometers(nm)) a KrF laser (248 nm), or an ArF laser (193 nm), targeted upon arotating pellet of the desired material at an incident angle of about45°. The substrate can be mounted upon a heated holder rotated at about0.5 revolutions per minute (rpm) to minimize thickness variations in theresultant film or layer. The substrate can be heated during thedeposition at temperatures from about 500° C. to about 950° C.,preferably from about 700° C. to about 850° C. An oxygen atmosphere offrom about 0.1 millitorr (mTorr) to about 500 mTorr, preferably fromabout 100 mTorr to about 250 mTorr, can be maintained within thedeposition chamber during the deposition. Distance between the substrateholder and the pellet can generally be from about 4 centimeters (cm) toabout 10 cm.

The rate of formation of thin films or layers can be varied from about0.1 Angstrom per second (Å/s) to about 200 Å/s by changing the laserrepetition rate from about 1 hertz (Hz) to about 200 Hz. As laser beamdivergence is a function of the repetition rate, the beam profile can bemonitored after any change in repetition rate and the lens focaldistance adjusted to maintain a constant laser energy density upon thetarget pellet. Generally, the laser beam can have dimensions of about 3millimeters (mm) by 4 mm with an average energy density of from about 1to about 5 joules per square centimeter (J/cm²), preferably from about1.5 to about 3 J/cm².

The dielectric composite materials of the present invention can beformed as ceramics or as thin films. The dielectric composite materialsof the present invention are preferably formed as thin films for bothtunable dielectric applications and for capacitor applications. Intunable microwave applications, the thin films of the dielectriccomposite are generally from about 2000 Angstroms to about 2 microns inthickness, more preferably from about 3000 Angstroms to about 1 micronin: thickness. In capacitor applications, the thin films of thedielectric composite are generally less than about 1000 Angstromsthickness, preferably from about 200 Angstroms to about 500 Angstroms inthickness.

Composite Ba_(0.6)Sr_(0.4)TiO₃/TiO₂ (90/10 weight percent) andBa_(0.6)Sr_(0.4)TiO₃/TiO₂ (50/50 weight percent) thin films have beendeposited on magnesium oxide substrates by pulsed laser deposition.X-ray diffraction, transmission electron microscopy (TEM), anddielectric measurements have been used to characterize the films. Bothx-ray diffraction and TEM studies have shown that the thin filmcomposites had inclusions of TiO₂. FIG. 1 shows the x-ray diffractionpattern of a Ba_(0.6)Sr_(0.4)TiO₃/TiO₂ (90/10 weight percent) film. FIG.2 shows the x-ray diffraction pattern of a Ba_(0.6)Sr_(0.4)TiO₃/TiO₂(50/50 weight percent) film. As can be seen from FIGS. 1 and 2, bothfilms clearly exhibited a TiO₂ phase. Visual evidence from the TEMsupports this conclusion as well.

Dielectric measurements showed obvious reduction of dielectric loss ofthe composites. The maximum dielectric losses are 0.001 and 0.006 at 1MHz for Ba_(0.6)Sr_(0.4)TiO₃/TiO₂ (90/10 weight percent) andBa_(0.6)Sr_(0.4)TiO₃/TiO₂ (50/50 weight percent), respectively, comparedto a value of 0.02 for pure Ba_(0.6)Sr_(0.4)TiO₃. The dielectrictunability is related to the percentage addition of TiO₂. For example,Ba_(0.6)Sr_(0.4)TiO₃/TiO₂ (50/50 weight percent) composite films showedno detectable tunability at a field up to 200 KV/cm but 37% forBa_(0.6)Sr_(0.4)TiO_(3/)TiO₂ (90/10 weight percent) films.

As mentioned above, the existing approaches suffer from the significantreduction of the dielectric constant and the dielectric tunability. Thepresent invention shows much improved material performance. Thedielectric constant of TiO₂ is around 100. Its dielectric loss is around10⁻⁴. The addition of TiO₂ into Ba_(1−x)Sr_(x)TiO₃ does not reduce thedielectric constant of the composite nearly as much as when alternativeoxides are used as the dopant. The real advantages are that bycontrolling the amount of TiO₂ added to the Ba_(1−x)Sr_(x)TiO₃ not onlycan the dielectric constant and the tunability be adjusted but thedielectric loss of the composite can be reduced.

The composite materials of the present invention will find many uses inmicroelectronic applications in the radio frequency and microwavefrequency regimes. The composite materials can be used as dielectricmedia for high performance thin film capacitors. More importantly, theycan be used for electrically tunable microwave components such asfilters and phase shifters that are important in defense electronics andcivilian telecommunications.

The present invention is more particularly described in the followingexamples which are intended as illustrative only, since numerousmodifications and variations will be apparent to those skilled in theart.

EXAMPLE 1

The microstructure of TiO₂ and Ba_(1−x)Sr_(x)TiO₃ composite thin filmson MgO substrates was examined by transmission electron microscopy (TEM)and high resolution electron microscopy (HREM) in cross-section in the[100] direction. Cross-sectional TEM micrographs of the TiO₂ andBa_(1−x)Sr_(x)TiO₃ composite thin films on MgO substrates revealed thefollowing. Two distinct phases, one of TiO₂ and one ofBa_(1−x)Sr_(x)TiO₃ were observed.

To assess the microwave losses of the epitaxial TiO₂ andBa_(1−x)Sr_(x)TiO₃ composite thin films on MgO substrates, a coplanarwaveguide structure as shown in FIG. 3 was fabricated incorporating a2000 Å thick composite thin film of TiO₂ and Ba_(1−x)Sr_(x)TiO₃.Compositions including weight percentages of BST/TiO₂ of 50/50, 90/10,95/5, 99/1 and 100/0 were measured. Gold contact pads (0.2 micron thick)were deposited by rf sputtering and patterned by a lift-off technique.The finished devices were annealed at 450° C. in oxygen. The device hada centerline width of 20 microns and a gap width of 40 microns betweenthe centerline and the groundplates. The device was designed andoperated in the manner of the electrically tunable coplanar transmissionline resonator as described by Findikoglu et al., Appl. Phys. Lett.,vol. 66, pp. 3674-3676 (1995), wherein YBCO/STO bilayers were growndirectly on [001] LaAlO₃ substrates, such details incorporated herein byreference.

The structural properties of the films were characterized by x-raydiffraction measurements using a Siemens D5000 four circlediffractometer with Cu Kα radiation. In FIG. 1 is shown the XRD datafrom the sample including BST to TiO₂ or 90/10. Diffraction lines ofboth TiO₂ and Ba_(1−x)Sr_(x)TiO₃ phases are present.

The following table shows the measured dielectric properties of theBa_(0.6)Sr_(0.4)TiO₃/TiO₂ composite films with different weightpercentages of BSTO and TiO₂. The tunability is defined as[C(0V)−C(V)]/C(0V). The electric field was 200 kV/cm. The frequency was1 MHz. The dielectric losses outlined in the table are the maximumvalues. The K factor is defined as tunability/loss. The commonly usedfigure of merit for the quality of frequency and phase agile materialsis the ratio of the tunability to the loss, the so-called K factor.

BSTO/TiO₂ 50/50 90/10 95/5 99/1 100/0 (weight %) Dielectric 120 428 10501100 1180 Constant Tunability (%) 0 37 60 64 70 Dielectric Loss 0.0010.006 0.02 0.02 0.02 K 0 62 30 32 35

The present results demonstrate that selected BSTO/TiO₂ composites canbe characterized as tunable dielectric materials. For example, theBSTO/TiO₂ composite having weight percentages of about 90/10 had hightunability within the tested voltage range with a high K value and lowdielectric loss.

EXAMPLE 2

A thin film of BSTO/TiO₂ of 50/50 weight percent was formed on a MgOsubstrate as in Example 1. At a high frequency of about 2.2 GHz, theresultant material was found to be non-tunable dielectric materialwithin the tested voltage range and had a dielectric loss of less than0.001, a value consistent with the low frequency measurement ofExample 1. Applications for such a material include use as a capacitorin high frequency applications.

Although the present invention has been described with reference tospecific details, it is not intended that such details should beregarded as limitations upon the scope of the invention, except as andto the extent that they are included in the accompanying claims.

What is claimed is:
 1. A dielectric composite material comprising atleast two crystal phases of different components with TiO₂ as a firstcomponent and a material selected from the group consisting ofBa_(1−x)Sr_(x)TiO₃ where x is from 0.3 to 0.7, Pb_(1−x)Ca_(x)TiO₃ wherex is from 0.4 to 0.7, Sr_(1−x)Pb_(x)TiO₃ where x is from 0.2 to 0.4,Ba_(1−x)Cd_(x)TiO₃ where x is from 0.02 to 0.1, BaTi_(1−x)Zr_(x)O₃ wherex is from 0.2 to 0.3, BaTi_(1−x)Sn_(x)O₃ where x is from 0.15 to 0.3,BaTi_(1−x)Hf_(x)O₃ where x is from 0.24 to 0.3, Pb_(1−1.3) _(La)_(x)TiO_(3+0.2x) where x is from 0.23 to 0.3,(BaTiO₃)_(x)(PbFe_(0.5)Nb_(0.5)O₃)_(1−x) where x is from 0.75 to 0.9,(PbTiO₃)_(x)(PbCo_(0.5)W_(0.5)O₃)_(1−x) where x is from 0.1 to 0.45,(PbTiO₃)_(x)(PbMg_(0.5)W_(0.5)O₃)_(1−x)where x is from 0.2 to 0.4, and(PbTiO₃)_(x)(PbFe_(0.5)Ta_(0.5)O₃)_(1−x)where x is from 0 to 0.2, as thesecond component.
 2. The dielectric composite material of claim 1wherein said dielectric composite material is a thin film and ischaracterized as epitaxial upon a substrate selected from the groupconsisting of lanthanum aluminum oxide, magnesium oxide, and neodymiumgadolinium oxide.
 3. The dielectric composite material of claim 1wherein said dielectric composite material is a thin film and ischaracterized as amorphous, polycrystalline or nanocrystalline upon asubstrate selected from the group consisting of semiconductors,insulators, metals and metal alloys.
 4. The dielectric compositematerial of claim 3 wherein said substrate is selected from the groupconsisting of silicon, sapphire and steel.
 5. The dielectric compositematerial of claim 1 wherein said dielectric composite material includesfrom about 45 percent by weight to about 55 percent by weight of TiO₂and from about 45 percent by weight to about 55 percent by weight ofBa_(1−x)Sr_(x)TiO₃.
 6. The dielectric composite material of claim 1wherein said dielectric composite material includes from about 7 percentby weight to about 40 percent by weight of TiO₂ and from about 60percent by weight to about 93 percent by weight of Ba_(1−x)Sr_(x)TiO₃and said dielectric composite material is characterized as a tunabledielectric material.
 7. The dielectric composite material of claim 1wherein said dielectric composite material includes about 10 percent byweight of TiO₂ and about 90 percent by weight of Ba_(1−x)Sr_(x)TiO₃ andsaid dielectric composite material is characterized as a tunabledielectric material.
 8. The dielectric composite material of claim 1wherein said dielectric composite material includes about 50 percent byweight of TiO₂ and about 50 percent by weight of Ba_(1−x)Sr_(x)TiO₃ andsaid dielectric composite material is characterized as having adielectric loss of 0.001 or less.
 9. A dielectric composite materialcomprising at least two crystal phases of different components, formedat high temperatures from TiO₂ and a material selected from the groupconsisting of Ba_(1−x)Sr_(x)TiO₃ where x is from 0.3 to 0.7,Pb_(1−x)Ca_(x)TiO₃ where x is from 0.4 to 0.7, Sr_(1−x)Pb_(x)TiO₃ wherex is from 0.2 to 0.4, Ba_(1−x)Cd_(x)TiO₃ where x is from 0.02 to 0.1,BaTi_(1−x)Zr_(x)O₃ where x is from 0.2 to 0.3, BaTi_(1−x)Sn_(x)O₃ wherex is from 0.15 to 0.3, BaTi_(1−x)Hf_(x)O₃ where x is from 0.24 to 0.3,Pb_(1−1.3x)La_(x)TiO_(3+0.2x) wherei x is from 0.23 to 0.3,(BaTiO₃)_(x)(PbFe_(0.5)Nb_(0.5)O₃)_(1−x) where x is from 0.75 to 0.9,(PbTiO₃)_(x)(PbCo_(0.5)W_(0.5)O₃)_(1−x) where x is from 0.1 to 0.45,(PbTiO₃)_(x)(PbMg_(0.5)W_(0.5)O₃)_(1−x) where x is from 0.2 to 0.4, and(PbTiO₃)_(x)(PbFe_(0.5)Ta_(0.5)O₃)_(1−x) where x is from 0 to 0.2. 10.The dielectric composite material of claim 9 wherein said dielectriccomposite material is a thin film and is characterized as epitaxial upona substrate selected from the group consisting of lanthanum aluminumoxide, magnesium oxide, and neodymium gadolinium oxide.
 11. Thedielectric composite material of claim 9 wherein said dielectriccomposite material is a thin film and is characterized as amorphous,polycrystalline or nanocrystalline upon a substrate selected from thegroup consisting of semiconductors, insulators, metals and metal alloys.12. The dielectric composite material of claim 11 wherein said substrateis selected from the group consisting of silicon, sapphire and steel.13. The dielectric composite material of claim 9 wherein said dielectriccomposite material includes from about 45 percent by weight to about 55percent by weight of TiO₂ and from about 45 percent by weight to about55 percent by weight of Ba_(1−x)Sr_(x)TiO_(3.)
 14. The dielectriccomposite material of claim 9 wherein said dielectric composite materialincludes from about 7 percent by weight to about 40 percent by weight ofTiO₂ and from about 60 percent by weight to about 93 percent by weightof Ba_(1−x)Sr_(x)TiO₃ and said dielectric composite material ischaracterized as a tunable dielectric material.
 15. The dielectriccomposite material of claim 9 wherein said dielectric composite materialincludes about 10 percent by weight of TiO₂ and about 90 percent byweight of Ba_(1−x)Sr_(x)TiO₃ and said dielectric composite material ischaracterized as a tunable dielectric material.
 16. The dielectriccomposite material of claim 9 wherein said dielectric composite materialincludes about 50 percent by weight of TiO₂ and about 50 percent byweight of Ba_(1−x)Sr_(x)TiO₃ and said dielectric composite material ischaracterized as having a dielectric loss of 0.001 or less.
 17. Aprocess of forming a thin film dielectric composite material includingat least two crystal phases of different components with TiO₂ as a firstcomponent and a material selected from the group consisting ofBa_(1−x)Sr_(x)TiO₃ where x is from 0.3 to 0.7, Pb_(1−x)Ca_(x)TiO₃ wherex is from 0.4 to 0.7, Sr_(1−x)Pb_(x)TiO₃ where x is from 0.2 to 0.4,Ba_(1−x)Cd_(x)TiO₃ where x is from 0.02 to 0.1, BaTi_(1−x)Zr_(x)O₃ wherex is from 0.2 to 0.3, BaTi_(1−x)Sn_(x)O₃ where x is from 0.15 to 0.3,BaTi_(1−x)Hf_(x)O₃ where x is from 0.24 to 0.3,Pb_(1−1.3x)La_(x)TiO_(3+0.2x) where x is from 0.23 to 0.3,(BaTiO₃)_(x)(PbFe_(0.5)Nb_(0.5)O₃)_(1−x) where x is from 0.75 to 0.9,(PbTiO₃)_(x)(PbCo_(0.5)W_(0.5)O₃)_(1−x) where x is from 0.1 to 0.45,(PbTiO₃)_(x)(PbMg_(0.5)W_(0.5)O₃)_(1−x) where x is from 0.2 to 0.4, and(PbTiO₃)_(x)(PbFe_(0.5)Ta_(0.5)O₃)_(1−x) where x is from 0 to 0.2, asthe second component comprising: forming a starting material including amixture of TiO₂ and the material selected from the group consisting ofBa_(1−x)Sr_(x)TiO₃, Pb_(1−x)Ca_(x)TiO₃, Sr_(1−x)Pb_(x)TiO₃,Ba_(1−x)Cd_(x)TiO₃, BaTi_(1−x)Zr_(x)O₃, BaTi_(1−x)Sn_(x)O₃,BaTi_(1−x)Hf_(x)O₃, Pb_(1−1.3x)La_(x)TiO_(3+0.2x),(BaTiO₃)_(x)(PbFe_(0.5)Nb_(0.5)O₃)_(1−x),(PbTiO₃)_(x)(PbCo_(0.5)W_(0.5)O₃)_(1−x),(PbTiO₃)_(x)(PbMg_(0.5)W_(0.5)O₃)_(1−x), and(PbTiO₃)_(x)(PbFe_(0.5)Ta0.5O₃)_(1−x); depositing a thin film of thestarting material on a substrate; and, heating the thin film of startingmaterial for time and at temperatures sufficient to form said thin filmdielectric composite material including at least two crystal phases ofdifferent components.
 18. The process of claim 17 wherein said substrateis selected from the group consisting of lanthanum aluminum oxide,magnesium oxide, and neodymium gadolinium oxide.
 19. The process ofclaim 17 wherein said substrate is selected from the group consisting ofsemiconductors, insulators, metals and metal alloys.
 20. The process ofclaim 17 wherein said substrate is selected from the group consisting ofsilicon, sapphire and steel.